This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A138144 #12 Jun 17 2017 03:56:10
%S A138144 1,11,111,1111,11011,110011,1100011,11000011,110000011,1100000011,
%T A138144 11000000011,110000000011,1100000000011,11000000000011,
%U A138144 110000000000011,1100000000000011,11000000000000011,110000000000000011
%N A138144 Palindromes formed from the reflected decimal expansion of the concatenation of 1, 1 and infinite 0's.
%C A138144 a(n) is also A147595(n) written in base 2. [From _Omar E. Pol_, Nov 08 2008]
%H A138144 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A138144 a(n) = 11+11*10^(n-2) for n>3. a(n) = 11*a(n-1)-10*a(n-2). G.f.: -x*(10*x^2-1)*(10*x^2+1) / ((x-1)*(10*x-1)). - _Colin Barker_, Sep 15 2013
%e A138144 n .... a(n)
%e A138144 1 .... 1
%e A138144 2 .... 11
%e A138144 3 .... 111
%e A138144 4 .... 1111
%e A138144 5 .... 11011
%e A138144 6 .... 110011
%e A138144 7 .... 1100011
%e A138144 8 .... 11000011
%e A138144 9 .... 110000011
%e A138144 10 ... 1100000011
%t A138144 LinearRecurrence[{11,-10},{1,11,111,1111,11011},20] (* _Harvey P. Dale_, Aug 21 2016 *)
%o A138144 (PARI) Vec(-x*(10*x^2-1)*(10*x^2+1)/((x-1)*(10*x-1)) + O(x^100)) \\ _Colin Barker_, Sep 15 2013
%Y A138144 Cf. A000533.
%Y A138144 Cf. A138118, A138119, A138120, A138145, A138146, A138721, A138826, A147595. [From _Omar E. Pol_, Nov 08 2008]
%K A138144 easy,nonn,base
%O A138144 1,2
%A A138144 _Omar E. Pol_, Mar 29 2008
%E A138144 Better definition. - _Omar E. Pol_, Nov 15 2008